Heat exchanger and method of assembling the same



J. E. WOODS E'l'AL 2,520,821

HEAT EXCHANGER AND METHOD OF ASSEMBLING THE SAME Aug. 29, 1950 2 Sheets-Sheet 1 Filed March 13, 1947 AT OR NEYS Aug. 29, 1950 J. E. WOODS EI'AL 2,520,821

HEAT EXCHANGER AND METHOD OF ASSEHBLING THE SAME Filed March 13, 1947 2 Sheets-Sheet 2 ATTORNEYS Patented Aug. 29, 1950 HEAT EXCHANGER AND METHOD O1? ASSEMBLING THE SAME John E. Woods, Cohasset, and Charles S. Martel,

Medtord, Masa, assignon,

by mesne assignments, to Standard-Thomson Corporation, 303- ton, Mass., a corporation oi Delaware Application March 13, 1947, Serial No.1734,470 8 Claims. (CL 257-128) The present invention relates to heat exchangers and methods 01' assembling the same,

and is more particularly concerned with heat exchangers having thin-wall closely spaced tubes such as are used for aircraft oil coolers.

The oil cooler described in the Woods application Serial No. 603,491, filed July 6, 1945, comprises a cooler having longitudinal bames to provide axial flow paths through the coolers. The core comprises a set oi. closely spaced thin wall tubes, preferably 01' aluminum. In the preferred form of the invention the tubes are brazed to the aluminum headers. The baiiles are inserted in suitable spaces on the sides of the core. As described in said application, each baflle is sealed to one of the headers. The particular construction there described involving the use of a rubberlike sealing member. The oil cooler specifically described in that application is a demountable cooler, namely one in which the baiiies may be removed for cleaning purposes although a similar arrangement may be used for a heat exchanger which is not intended to be disassembled.

The object of the present invention is to provide improvements in methods and means for sealing the bailles in heat exchangers of this general type. To this end the present invention comprises the heat exchanger hereinafter described and particularly defined in the claims.

In the accompanying drawings, Fig. l is a sectional view of a heat exchanger core according to the present invention; Fig. 2 is a section on line 2-2 of Fig. 1; Fig. 3 is an enlarged detail view taken on line 3-3 of Fig. 1; Fig. 4 is an enlarged end view of the parts shown in Fig. 3;

Fig. 5 is a detail showing-the preparation of the sealing foil; Fig. 6 is a perspective view showing the application of the sealing foil; and Fig. 7

2 groups. Between adjacent groups there is a space 16 preferably about .085" to accommodate the bailles. Five of such spaces are provided so that the cooler has six axial-flow passages. A completed cooler may have 3600 tubes or more, but for simplicity a relatively small number are shown inthe drawing. Bailles l8 areinserted inthe spaces l6. Each baille l8 comprises an aluminum sheet of about .025" thick. Each baille is provided with pressed spacer projections 20, protruding in both directions from the sheet to engage with tubes on opposite sides. Each baflle is the proper width to extend acrossa chord of the core and is provided with wings 22 which can be readily bent for engagement with the shell. The ballles are of less height than the wings to provide an oil flow'space 24. One edge of each baiile is adapted to be sealed against one of the headers, and the space 24 provides an oilflow passage between the groups oi tubes of the cooler. The oil-flow space 24 is arranged at opposite ends 01' the cooler for alternate bailles as will be obvious to those skilled in the art, in order that the'oil will be caused to flow along the six groups 01 tubes in series.

It is important that'the edge of the baffle opposite the space 24 be tightly sealed to the header. It'is impracticable to braze the baflle to the header after insertion of the tubes since is a view showing the construction of the filling material to prevent channeling.

The construction shown in the drawings comprises a core consisting of a large number of closely spaced thin wall tubes I0 protruding at opposite ends through header plates l2. Each header plate is provided with a circumferential flange It for attachment to a shell as will hereinafter be described. To illustrate the size and spacing of the tubes, each tube maybe about .268" in diameter and o! a wall thickness of about .005", spaced .313" on centers. The tubes are preferably 01' aluminum. The tubes are brazed to the headers by the method described in the Woods Patent No. 2,389,175 dated November 20, 1945. i

As shown in Fig. 1, the tubes are arranged in such an operation would require dipping of the core into molten "brazing material with consequent danger oi destroying some of the tubes. Furthermore, it is desirable to provide a construction which can be takenapart ii'desired.

According to the present invention, the baflles are inserted into the spacesli after the tubes v are assembled in the headers. The lengths of the wing portions 22 and the sizes of the positioning projections 20 are such that the baflles may readily be inserted.

To seal the edge against the header, a mass of metal foil is applied. This is conveniently applied by passing a thinroll of foil into the space between the edge of the headerand a row of tubes. As shown in Fig. 5, a sheet of foil 26 is rolled up on a thin metal strip 28. The foil is only about .001" thick and several convolutions will produce only a thin roll but it will be understood that the thickness is necessarily exaggerated in the drawing.

The roll of foil, still mounted on the bar 28,-is

then inserted into the space l6 at one side of the header. Another bar 30, preferably somewhat The bar 28 is thicker than the bar 28, is inserted into the space substantial amount of foil has been built up.

This operation is repeated several times until a Preferably a sumcient amount of foil is introduced V to build up a compacted mass to a depth of or more.

the header plates may be bowed or dished in 'one 1 direction or the other. It will be understood that 1 by repeated application of rolls of foil, a suflicient body of packed or massed foil may be built up to fill any spaces due to distortion of the header. 1

The mass of foil is flrmlylocked in place; it secures the baille firmly in position and forms an oil-tight seal which cannot be weakened or de stroyed in normal service.

If at any time it is necessary to remove a baflle,

the foil can be worked out by introducing a thin.

Owing to the process of manufacture, some of Having thus described the invention, we claim:

1. Heat exchange apparatus comprising a core having a large number of closely spaced thin-wall tubes and headers through which the ends of the tubes project, baflles extending across the core between selected rows of tubes to form axial-flow passes, a mass of pressed foil for sealing one edge of each baflle against a header, the mass of foil extending the full length of the contacting edge between the baflle and the header, and being packed tightly against said edge, alternate baflies having said edgesealed against-opposite headers, each baille having a large oil-pass space at the edge opposite the sealed edge and having side portions extending between headers, a shell surrounding the core, and means for securing the After insertion of the baflles, the wings 22 pro- I trude somewhat beyond the edges of the flanges ll. The wings are bent over slightly as shown in Fig. 1. The tank or shell 32 is ultimately to be ciently close to the shell. If the shellwere ap- .45 channeling of liquid between the outer tubes and plied without filling in suchspaces, excessive the shell might occur. -The filling-material 33.] preferably comprises several tubes 3! arranged in a row and held together with caps 36 made by. folding foil around their ends, as shown in Fig. 7. The tubes 34 are preferably of a soft alloy so,

that they can be jammed into place against the tubes of the core: the foil 36 issimilar to, but heavier than, the foil 26. The tubes may have small openings punched near opposite ends to allowany liquid that may get inside to drain out of the tubes.

The filling tube assemblies 33. a"... pressed into place around the core and between the bamesa Then the wings 22 are bent to lock the filling tube shell to the headers.

2. Heat exchange apparatus comprising a core having a large number of closely spaced thin-wall tubes and headers through which the ends of the tubes project, baiiles extending across the core between selected rows of tubes to form axial-flow passes, a mass of compacted pressed foil extending along one entire edge of each baflle to seal the baflle against a header, the foil being interlocked with adjacent tubes.

3. Heat exchange apparatus comprising a core having a large number of closely spaced thin-wall tubes and headers through which the ends of the tubes project, baifies extending across the core between selected rows of tubes to form axial-flow passes, a mass of pressed foil for sealing one edge of each baffle against a header, the mass of foil extending the full length of the contacting edge between the baffle and the header, and being packed tightly against said edge, alternate'baflles having said edge sealedagainst opposite headers, each baflie having a large oil-pass space at the edge opposite the sealed edge and having bent wing portions extending outwardly beyond the headers, a shell surrounding the core and engag ing the wing portions of the bailies throughout their length, and means forsecuring the shell to the headers.

4. Heat exchange apparatus comprising a core 2 having a large number of closely spaced thin-wall tubes and headers through which the ends of the tubes project, bailles extending across the core between selected rows of tubes to form axial-flow passes, a mass of compacted pressed foil extend-,

ing alone one edge of each baffle to seal the baflle against a header, the mass of foil extending the assemblies in place and also to allow the tank or shell 32 to be slipped over the,core. The tank may be of any suitable form but as shown in Fig.

2 it is provid d the usual casting 38 to accommodate the control valve assembly. The inside diameter of the tank is such as to slide over the flanges ll of the headers. The tank is started over one header and is pushed down along the wings 22. them to fit tightly against the tank. The tank The resiliency of' the wings causes.

may be secured to the headers by any of the fas tening means shown in the Woods application No. i

603,4;91 or if the unit is not'intended to be taken full length of the contacting edge between the baiile and the header, and being packed tightly against said edge, the foil being interlocked with adjacent tubes, alternate bailles having said edge sealed against opposite headers, each baille having a large oil-pass space at the edge opposite the sealed edge and having bentwing portions extending outwardly beyond the headers, a shell surrounding the core and engaging the wing portions of the bafiies throughout their length, and means for securing the shell to the headers.

' 5. Heat exchange apparatus comprising a core having a large number of closely spaced thin-wall.

tubes and headers through which the ends of the tubes project, bafiles extending across the core between selected rows of tubes to form axial-flow passes, a mass of pressed foil for sealing one edge of each baflle against a header, the mass of foil extending the full length of the contacting edge between the baiile and the header, and being packed tightly against said edge, alternate bailies having said edge sealed against opposite headers,

6. The method of making a baiiled thin-wall tube heat exchanger which consists in inserting a battle into the inter-tube space of a heat exchanger core, inserting a roll of metal foil wrapped on a thin bar at the Joint between the header and baiiie withdrawing said bar from the roll of foil, inserting a narrow bar above the roll of foil, and pressing downwardly on said bar to compact the foil firmly into said Joint and substantially uniformly along the entire Joint.

7. Heat exchange apparatus comprising acore having a large number of closely spaced thinwall tubes and headers through which the ends of the tubes project, baflies extending acm the core 5 between selected rows of tubes to form axial-flow passes, a roll of foil compr into the space along the line of contact of each baiiie with a header for sealing the edge of said bame against said header. roll of foil extending the full length of the contacting edge of the baiile with the header, alternate bailles having said edge sealed against opposite headers, each baflie having a large oil-pass space at the edge opposite the sealed edge and having side portions extending between headers, a shell surrounding the core, and means for securing the shell to the headers.

8. The method of. making a baiiied thin-wall tube heat exchanger which consists in inserting a baiiie into the inter-tube space of a heat exchanger core, inserting a roll of metal foil wrapped on a thin bar at the joint between the.

header and baile, withdrawing said bar from the roll of foil, and pressing the foil firmly into said joint.

JOHN E. WOODS. CHARLES 8. mm.

REFERENCES CITED The following references are of record in the flle 01' this patent:

UNITED STATE PATENTS Certificate of Correction Patent No. 2,520,821 August 29, 1950 JOHN E. WOODS ET AL.

It is hereby certified that error appears in the printed specification of the above numbered patent requiring correction as follows:

Column 4, lines 71 to 74, strike out the Words and comma the mass of foil extending the full length of the contacting edge between the bafile and the header, and being packed tightly against said edge,;

and that the said Letters Patent should be read as corrected above, so that the same may conform to the record of the case in the Patent Ofiice.

Signed and sealed this 12th day of December, A. D. 1950.

THOMAS F. MURPHY,

Assistant Commissioner of Patents. 

